Patent Number: 7,733,136

Title: Frequency synthesizer

Abstract: A frequency synthesizer includes: a fractional-N synthesizer configured to provide, in a locked condition, an output signal with an output frequency based on an input signal with a reference frequency, the fractional-N synthesizer including a charge pump outputting a current to be calibrated; a lock detector coupled to the fractional-N synthesizer to detect the locked condition, the lock detector being configured to send a first signal indicating the detection; a calibration component coupled to the lock detector and the fractional-N synthesizer, the calibration component being configured to provide a second signal to calibrate the current after receiving the first signal, based on a voltage sampled from the fractional-N synthesizer; and a current source array coupled to the calibration component and the fractional N synthesizer, the current source array being configured to calibrate the current based on the second signal.

Inventors: Chen; Chih-Hung (Kaohsiung, TW), Kuo; Ming-Ching (Hsinchu, TW), Kao; Shiau-Wen (Hsinchu, TW)

Assignee: Industrial Technology Research Institute

International Classification: H03L 7/06 (20060101)

Expiration Date: 2022-06-08 0:00:00